The Neuronotropic effect of superior cervical ganglion (SCG) grafts has been extended to the olfactory bulb, where granule cells and, possibly, other interneurons migrate anomalously and postnatally toward the graft. The column of migrating cells includes astrocytes which migrate with microglial cells and neurons to push aside glomeruli. Within the transplant, the number of neurons that survive depends on the availability of target tissue: the blood vessels of the pia and choroid plexus. Bilateral removal of the rat's own SCG at the time of transplantation increases the number of surviving ganglion cells about 4-fold during the sixth month after grafting. In regenerating hypoglossal neurons of monkey, there is a very modest rise in non-neuronal enolase concurrent with a pronounced fall in neuron-specific enolase (NSE). If the regenerating nerve, in rats, is allowed to reinnervate the tongue, the level of NSE approaches near-normal levels in 60 days. If the nerve is prevented from doing so, the NSE level remains low.